amqmxmsstd.dll是必须使用的库，可以从MQ v9.1.1中获得。以下是信息中心链接，该链接讨论将XMS与Microsoft .NET Core一起使用。
将XMS与Microsoft .NET Core配合使用

amqmxmsstd.dll is the library that has to be used and it is available from MQ v9.1.1. Following is the infocenter link which talks about using XMS with Microsoft .NET Core. Using XMS with Microsoft .NET Core

您需要同时使用amqmdnetstd.dll和amqmxmsstd.dll来开发XMS .NET应用程序，并且这两个dll都使用.NET Standard.Following信息中心链接介绍了用于构建这些库的框架。
为.NET Standard安装IBM MQ类

You would need both amqmdnetstd.dll and amqmxmsstd.dll for developing XMS .NET applications and both these dll's are built using .NET Standard.Following infocenter link talks about the framework used to build these libraries. Installing IBM MQ classes for .NET Standard

正如Josh指出的那样，您可以使用MQ Redist客户端来获取库。
从 IBM MQ Redist客户端

As Josh pointed out,you can use MQ Redist client to get libraries. Download "9.1.1.0-IBM-MQC-Redist-Win64" from IBM MQ Redist clients